Interrelated power delivery controls – including engine control – Plural engines – Electric engine
Reexamination Certificate
1999-08-31
2001-05-22
Estremsky, Sherry (Department: 3681)
Interrelated power delivery controls, including engine control
Plural engines
Electric engine
C477S007000, C180S065100
Reexamination Certificate
active
06234932
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a hybrid vehicle having an internal combustion engine and a motor as a vehicle drive source, and, more particularly, to an apparatus for controlling the hybrid vehicle.
2. Description of the Related Background Art
Hybrid vehicles having an engine and a motor as a drive source are known. A control apparatus for controlling such a hybrid vehicle is disclosed in Japanese Laid-Open Patent Publication No. 3(1991)-121928, for example.
The control apparatus drives a motor in accordance with the operating condition of a vehicle as well as controls the output of an engine. Specifically, the operation mode of the motor is determined in accordance with the operating condition of the vehicle. In the acceleration mode, electric drive power is supplied to the motor to perform an assist operation for assisting the output of the engine. In the deceleration mode, regenerative operation is performed to store regenerative electric power produced by the motor to a capacitor as a high-voltage storage device. The electric power stored in the capacitor is used as electric power motor drive in the assist operation.
Recently, other than the acceleration mode and deceleration mode, a cruising mode for controlling a constant speed of a vehicle has been suggested. In the cruising mode, either the assist operation or regenerative operation is selectively performed by taking into account operating conditions such as the speed of the vehicle and the state of the capacitor charge.
However, it has been a difficult problem to distinguish clearly between the acceleration mode and the cruising mode in accordance with the operating conditions of a vehicle. That is, it was necessary to distinguish the operating conditions under which the operation mode of the motor is to be changed from the acceleration mode to the cruising mode and the operating conditions under which the operation mode is to be changed from the cruising mode to the acceleration mode, so as to improve fuel consumption of the engine and ensure drivability.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a control apparatus for a hybrid vehicle, which enables operation mode change between the acceleration mode and cruising mode with fuel consumption of the engine being improved and drivability bing ensured.
A control apparatus for a hybrid vehicle having an internal combustion engine and a dynamotor as drive sources of the vehicle, the dynamotor operating as a motor for assisting the output of the internal combustion engine and operating as a generator for regenerating running energy of the vehicle, the apparatus comprising: control means, in accordance with operating conditions of the vehicle, for controlling an assist operation for supplying electric power from a storage device to the dynamotor and a regenerative operation for charging the storage device by the generated power of the dynamotor; and determination means for determining that the operating condition of the vehicle is in one of a plurality of operation modes including at least, an acceleration mode for performing an assist operation, a cruising mode for selectively performing the assist operation and a regenerative operation; wherein the determination means determines either the acceleration mode or the cruising mode in accordance with an engine rotational speed and a throttle valve opening degree of the internal combustion engine, or a vehicle speed of the vehicle and the throttle valve opening degree.
According to the control apparatus for a hybrid vehicle, since the operating mode is determined to be either the acceleration mode or the cruising mode in response to the engine rotational speed of an internal combustion engine and throttle valve opening degree or the vehicle speed of the vehicle and throttle valve opening degree, the operation mode can be changed from the acceleration to cruising mode so as to improve the fuel consumption of the engine and ensure good drivability.
Furthermore, in the control apparatus for a hybrid vehicle according to the present invention, the acceleration mode is determined when the throttle valve opening degree has exceeded the engine rotational speed or the acceleration mode start threshold value corresponding to the vehicle speed and the cruising mode is determined when the throttle valve opening degree has fallen below the acceleration mode end threshold value which is less than the acceleration mode start threshold value in response to the engine rotational speed or the speed of the vehicle. And an undesired mode variation between the acceleration mode and the cruising mode, caused by a slight operation variation of the throttle valve, can be suppressed for improving drivability.
Still furthermore, in the control apparatus for a hybrid vehicle according to the present invention, the control means includes data maps for setting the assist amount showing an electric power level to be supplied from the storage device to the dynamotor have parameters of the engine rotational speed and the throttle valve opening degree and are provide for as many as the number that is determined by the gear ratio of a transmission and an air/fuel ratio of the supply mixture of the internal combustion engine. The control means also detects the gear ratio of the transmission and the air/fuel ratio of the supply mixture of the internal combustion engine; selects a data map corresponding to respective detection results of the gear ratio of the transmission and the air/fuel ratio of the supply mixture of the internal combustion engine from the data maps; sets an assist amount corresponding to the engine rotational speed and the throttle valve opening degree by using the selected data map; corrects the assist amount thus set in accordance with the output voltage of the storage device; and performs the assist operation in accordance with the corrected assist amount.
With this configuration, according to the control apparatus of the present invention, not only are the engine rotational speed and throttle valve opening degree taken into account but also the operating conditions of the transmission resulting from the operator and air/fuel ratio of the supply mixture. Thus, fuel consumption of the engine can be reduced and at the same time the setting of the assist amount can be optimized to operate the motor at high efficiency.
In the control apparatus for a hybrid vehicle according to the present invention, the acceleration mode start threshold value and the acceleration mode end threshold value are gradually increased while the vehicle is climbing a sloping road or running at high speed, and the acceleration mode start threshold value and the acceleration mode end threshold value are gradually decreased when the vehicle is not climbing a sloping road or running at high speed. Accordingly, while the vehicle is climbing a sloping road or traveling at high speed, the storage device can be charged by the regeneration operation in the cruising mode and unnecessary use of the electric power stored in the storage device can be prevented.
Furthermore, in the control apparatus for a hybrid vehicle according to the present invention, the acceleration mode start threshold value and the acceleration mode end threshold value are gradually increased when a variation of the throttle valve opening degree per unit time is smaller than an opening level variation corresponding to the electric power of the storage device. Thus, the storage device can be charged by the regenerative operation with the operating mode shifted comparatively to the cruising mode even in a case of a large opening level variation of the throttle valve where the storage device has a slight amount of power left.
Still furthermore, in the control apparatus for a hybrid vehicle according to the present invention, the acceleration mode start threshold value and the acceleration mode end threshold value are initialized in the case where a variation of the throttle valve opening degree per unit time
Iwata Youichi
Izumiura Atsushi
Kiyomiya Takashi
Konno Fumihiko
Kuroda Shigetaka
Armstrong Westerman Hattori McLeland & Naughton LLP
Estremsky Sherry
Honda Giken Kogyo Kabushiki Kaisha
Lewis Tisha D.
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